Janet Jackson was forced to postpone upcoming tour dates last month, as she revealed to fans she's got surgery scheduled.

But it's now claimed her family have been left "terrified" as doctors reportedly found a growth on her vocal cords.

“Doctors found a growth on Janet’s vocal cords that could be serious,” a source told Radar Online. “It’s a medical condition that has to be taken care of immediately.”

Janet previously revealed she had surgery scheduled, but is yet to comment on exactly what it will be.

Janet Jackson was forced to postpone (Image: Splash)

The site claims her family are now "terrified" she could be facing a "cancer scare".

“They are all so scared that Janet may have cancer,” a source reportedly said. “The situation is really quite baffling because Janet does not smoke cigarettes and she lives a really healthy lifestyle.”

Janet postponed her Unbreakable Tour in December - making the announcement on her Instagram account.

The star kicked off her world tour in Vancouver in August and it was due to start again in January and run through to June.

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Writing on her official account, she said: “Hey you guys… Happy Holidays to each and every one of you. I need you to know, I learned today, from my doctors that I must have surgery soon.

"It breaks my heart to tell you that I am forced to postpone the Unbreakable Tour until the spring. Every date will be rescheduled."

She told fans to keep their tickets and said they would be honoured when the new schedule is announced.

"Please pray for me, my family and our entire company during this difficult time. There will be no further comment.

"I love you all so much and am ever grateful for your understanding and your love. Gon' b alright."